Washing machine with improved balancing characteristics and control method thereof

ABSTRACT

A washing machine with improved balancing characteristics includes a drum; a motor configured to rotate the drum; and a memory configured to store a no-load imbalance value of the washing machine and a threshold load imbalance value of the washing machine, wherein the no-load imbalance value is measured from an imbalance occurring during a rotation of the drum having no laundry therein. Further, the washing machine includes a control unit configured to calculate the threshold load imbalance value using the measured no-load imbalance value, compare an actual load imbalance value with the threshold load imbalance value and determine whether to stop a rotation of the drum based on the comparison, wherein the actual load imbalance value is determined from an imbalance occurring during a rotation of the drum having laundry therein.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority from Korean Patent Application No. 10-2013-0160019, filed on Dec. 20, 2013, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

Embodiments of the present invention relate to a washing machine and a method of controlling the washing machine, and more particularly, to a drum type washing machine and a control method thereof having improved balancing characteristics while maximizing balancing capabilities of the washing machine.

BACKGROUND

In general, a drum type washing machine includes a cabinet that forms an exterior of the washing machine, a tub in the cabinet configured to contain washing water (e.g., detergent-containing water), a rotatable drum in the tub configured to receive the laundry, a motor in or under the tub configured to provide rotational force to the drum, a water supply device configured to supply water to the tub, and a drainage device configured to discharge the washing water from the tub to the outside of the cabinet after the washing operation is terminated

The washing machine performs a series of processes including a washing cycle for removing dirt and pollutants from the laundry using water and detergent, a rinsing cycle for removing detergent from the laundry using clean water, and a water removal cycle (or a spin-dry cycle) using rotational movement of the rotary drum.

While the drum rotates, the laundry may not be distributed uniformly inside the drum, and an uneven distribution of the laundry may result when the laundry piles up in some regions as shown in FIG. 1. Particularly in the spin-dry cycle when the drum is rotated at very high speeds, the imbalanced distribution of the load can causes severe vibration and noise. Theses vibrations and noise not only result in consumer dissatisfaction but also cause the machine to wear out. Further, due to eccentric rotation of the drum, components such as the drum, the motor or the like may be damaged.

Therefore, in order to solve the above-mentioned problems, a conventional washing machine performs balance control including determining an actual load imbalance and temporarily stopping the spinning of the drum if the actual load imbalance exceeds a certain threshold, which will be referred to as a threshold load imbalance value hereinafter.

In this regard, in order to achieve a more exact and efficient balance control, it is important to determine the threshold load imbalance value reflecting specific characteristics of each washing machine.

The threshold load imbalance value, as will be further explained below, is a maximum load imbalance value of the washing machine minus a no-load imbalance value of the washing machine. The maximum load imbalance value is a limit beyond which the washing machine cannot withstand any more the imbalance occurring during rotation of the drum having laundry therein. The no-load imbalance value is an amount of imbalance occurring during rotation of the drum having no laundry therein.

While the maximum load imbalance value is a predetermined value that is same for the same model of washing machines. However, the no-load imbalance value may differ among the same model of washing machines, due to different characteristics of each individual washing machine, such as tolerance variations of a counter electromotive force of a motor in the washing machine and/or tolerance variations in manufacturing and assembling the washing machine. In other words, even if two washing machines are manufactured in accordance with the same specification, the no-load imbalance values of the two washing machines may be different from each other because, for example, axes of rotation may not be coincident with each other due to tolerances and/or variations in manufacturing and assembling.

In prior art, a threshold load imbalance value of the washing machine was set to an arbitrary value lower than a maximum load imbalance value by a certain margin, without considering different characteristics of each individual washing machine, or the no-load imbalance value of each individual washing machine. Since the margin is usually set to a greater value than the no-load imbalance value of the washing machine, a conventional washing machine has to stop rotation of a drum even though the washing machine can withstand a more severe imbalance. Therefore, it may be beneficial to adjust the load imbalance value by reflecting characteristics of the washing machine and/or a no-load imbalance value of the individual washing machine.

SUMMARY

In view of the above, one or more embodiments of the present invention provides a drum type washing machine with improved balancing characteristics and a method of controlling the washing machine, wherein a no-load imbalance value of the washing machine is measured, and a threshold load imbalance value is determined using the measured no-load imbalance value. The no-load imbalance value depends on characteristics of an individual (e.g., each) washing machine, such as tolerances and/or variations of the motor (e.g., a counter electromotive force of the motor) in the washing machine and/or tolerances and/or variations in manufacturing and assembling the washing machine.

In accordance with one or more aspects of the present invention, a drum type washing machine having improved balancing characteristics includes a drum; a motor configured to rotate the drum; a memory configured to store a no-load imbalance value of the washing machine and a threshold load imbalance value of the washing machine (which may be determined using the measured no-load imbalance value), wherein the no-load imbalance value is measured or otherwise determined from an imbalance occurring during rotation of the drum having no laundry in it (e.g., using an empty drum); and a control unit configured to calculate the threshold load imbalance value using the measured no-load imbalance value, and compare an actual load imbalance value with the threshold load imbalance value and determine whether to stop a rotation of the drum based on the comparison, wherein the actual load imbalance value is measured or otherwise determined from an imbalance occurring during rotation of the drum having laundry therein.

Further, the threshold load imbalance value may be calculated by subtracting the no-load imbalance value from a maximum load imbalance value of the washing machine.

Further, the maximum load imbalance value may be a limit beyond which the washing machine cannot withstand any more the imbalance occurring during the rotation of the drum having laundry therein. The maximum load imbalance value may be a pre-determined value for washing machines manufactured in accordance with the same specification (e.g., the same model of washing machine).

Further, the no-load imbalance value of the washing machine may equal or differ from that of another washing machine manufactured in accordance with the same specification (or characteristics or performance targets). The no-load imbalance value may depend on characteristics of the motor in the washing machine and/or on tolerances and/or variations in manufacturing and assembling.

In accordance with one or more other aspects of the present invention, a method for calculating a threshold load imbalance value of a drum type washing machine comprises measuring a no-load imbalance value from an imbalance occurring during rotation of a drum having no laundry therein; and calculating an threshold load imbalance value of the washing machine using the measured no-load imbalance value.

Calculating the threshold load imbalance value may include reading a maximum load imbalance value of the washing machine; and subtracting the no-load imbalance value from the maximum load imbalance value.

Further, the maximum load imbalance value of the washing machine may be a limit beyond which the washing machine cannot withstand any more the imbalance occurring during a rotation of the drum having laundry therein. The maximum load imbalance value may be a pre-determined value for washing machines manufactured in accordance with the same specification.

Further, the no-load imbalance value of the washing machine may differ from or be the same as that of another washing machine manufactured in accordance with the same specification, and may depend on characteristics of the motor in the washing machine and/or tolerances and/or variations in manufacturing and assembling the washing machine.

According to embodiments of the present invention, it is possible to improve balancing characteristics of the washing machine while maximizing balancing capabilities of the washing machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is an exemplary view illustrating an imbalanced state occurring in a washing machine;

FIG. 2 is a detailed block diagram of a washing machine with an improved balancing characteristic in accordance with exemplary embodiments of the present invention; and

FIG. 3 is a flow chart of an exemplary process for setting the threshold load imbalance value of a washing machine in accordance with embodiment(s) of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here.

One or more exemplary embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which one or more exemplary embodiments of the disclosure can be easily determined by those skilled in the art. As those skilled in the art will realize, the described exemplary embodiments may be modified in various different ways, all without departing from the spirit or scope of the present disclosure, which is not limited to the exemplary embodiments described herein.

It is noted that the drawings are schematic and are not necessarily dimensionally illustrated. Relative sizes and proportions of parts in the drawings may be exaggerated or reduced in their sizes, and a predetermined or recited size is just exemplary and not limiting. The same reference numerals designate the same structures, elements, or parts illustrated in two or more drawings to exhibit the same or similar characteristics.

The exemplary embodiments of the present disclosure illustrate ideal embodiments of the present disclosure in more detail. As a result, various modifications of the drawings are expected. Accordingly, the exemplary embodiments are not limited to a specific form or illustrated region, and for example, include a modification of form by manufacturing.

Hereinafter, a washing machine 200 according to exemplary embodiments of the present disclosure will be described with reference to FIG. 2. FIG. 2 is a detailed block diagram of a washing machine 200 having improved balancing characteristics in accordance with exemplary embodiments of the present disclosure. As shown in FIG. 2, the washing machine 200 may include a drum 202, a drum driving motor 204, an operating panel 206, a memory 208, and a control unit 214, and the like.

Hereinafter, the operation of the respective features of the washing machine 200 according to exemplary embodiments of the present disclosure will be described in detail with reference to FIG. 2.

First of all, the drum 202 is configured to contain laundry 201 therein. The drum 202 is positioned inside a cabinet of the washing machine 200 and is rotated by the drum rotating motor 204 to wash or spin-dry the laundry 201.

The drum driving motor 204 provides one of a plurality of different torques or rotation speeds to the drum 202, depending on the cycle of the washing machine 200 (e.g., a washing cycle, rinsing cycle, a spin-dry cycle, or a drying cycle) to rotate the drum 202 containing the laundry.

The operating panel 206 may include a key input unit through which a user inputs various operation commands or instructions, such as selection of washing cycles, a running or operation time for each cycle, reservation for operation (e.g., selection of a delay), and the like, and a display which displays the selected command or instruction and/or the operation state of the washing machine. When a key input is received from the key input unit, the operating panel 206 displays the selected operation and/or data, and/or generates data and/or a signal corresponding to the key input and applies the input data and/or signal to the control unit 214.

The memory 208 stores one or more programs for controlling the operations of the washing machine 200. Further, the memory 208 stores a no-load imbalance value 210 of the washing machine 200 (e.g., as an offset value) and a threshold load imbalance value 212 of the washing machine 200 calculated from or using the offset value, wherein the no-load imbalance value 210 is measured, determined or calculated from driving the drum driving motor 204 and/or or rotating the drum 202 with no load (i.e., no laundry in the drum 202, or an empty drum 202).

In this regard, the no-load imbalance value 210 may be different for each washing machine, depending on the characteristics of the drum driving motor 204 and the conditions in which the washing machine 200 is assembled. Also, the no-load imbalance value 210 may be different for each washing machine, depending on its manufacturing process. The no-load imbalance value 210 may be used as an offset value to adjust the threshold load imbalance value 212 of the washing machine 200.

The control unit 214 controls the overall operations of the washing machine 200 in accordance with the program(s) stored in the memory 208. Further, if an imbalance occurs during the operations of the washing machine 200, the control unit 214 determines whether to continue or stop the rotation of the drum 202 by calculating an actual load imbalance value caused by the imbalance and comparing the calculated actual load imbalance value with the threshold load imbalance value 212.

Hereinafter, one or more exemplary control processes performed by the control unit 214 to determine whether to continue or stop the rotation of the drum 202 during an imbalance will be described in further detail.

First of all, when the drum 202 rotates eccentrically during the washing cycle or spin-dry cycle of the washing machine 200, an imbalance may occur due to the discordance between the geometric center of the rotating shaft of the drum 202 and the centroid (or center of mass) of the laundry 201 in the drum 202.

When an imbalance occurs, the control unit 214 determines an actual load imbalance value.

In determining the actual load imbalance value, the control unit 214 may calculate it utilizing variations in the rotation speed of the drum driving motor 204. More specifically, the drum driving motor 204 may include a stator, a coil wound around the stator, and a rotator rotating by electromagnetic interaction with the coil. Here, the imbalance may cause a change in the rotation speed of the rotator. In other words, the control unit 214 may determine and/or use the variations in the rotation speed of the rotator of the drum driving motor 204 to determine the actual load imbalance value caused by the imbalance of the laundry in the drum 202.

Then, the control unit 214 compares the actual load imbalance value with the threshold load imbalance value 212 stored in the memory 208 of the washing machine 200.

In this regard, the threshold load imbalance value 212 of the washing machine 200 may be calculated by subtracting the no-load imbalance value 210 from the maximum load imbalance value. Here, the no-load imbalance value of a washing machine may be measured by operating the washing machine with no laundry therein (e.g., an empty drum 202), and the maximum load imbalance value of a washing machine is the maximum value of an imbalance which is tolerable by a washing machine. With the calculated threshold load imbalance value 212, the control unit 214 determines whether to continue or stop the rotation of the drum 202.

More specifically, when the actual load imbalance value calculated when an imbalance of the washing machine 200 occurs is larger than the threshold load imbalance value 212 stored in the memory 208, the control unit 214 determines that the washing machine is in a dangerous imbalance state and then stops rotation of the drum 202.

In the prior art described herein, a uniform threshold load imbalance value was set and was the same for each type or model of washing machine, and was calculated by subtracting a fixed value from the maximum load imbalance value of the particular type.

In contrast, in accordance with exemplary embodiments of the present disclosure, the control unit 214 calculates the threshold load imbalance value 212 for the individual washing machine by subtracting the no-load imbalance value 210 of the washing machine 200 (which is unique for each washing machine) from the maximum load imbalance value, thereby reflecting the characteristics of the respective or individual washing machine in setting the threshold load imbalance value 212.

For example, it is assumed that the no-load imbalance value for a type of washing machines may be in the range of 50 g to 150 g (grams), and the maximum load imbalance value is 600 g. Without considering the variations in the no-load imbalance values of such type of washing machines, the prior art technology arbitrarily determines a single threshold load imbalance value for all washing machines of that type to be 450 g, by subtracting the largest no-load imbalance value (150 g) from the maximum load imbalance value of 600 g, in order to stably control any imbalance (e.g., for the washing machines having the largest no-load imbalance value). According to the prior art, however, for a washing machine in which an actual no-load imbalance value is only 50 g, the threshold load imbalance value thereof is still 450 g, not 550 g, even though the washing machine may tolerate a load imbalance up to 550 g. That is to say, in accordance with the prior art, a threshold load imbalance value of a washing machine is set to a value (450 g for the above case) which is smaller than the actually tolerable load imbalance (550 g for the above case) of the washing machine having an actual no-load imbalance value of 50 g, which results in limiting the performance of the washing machine.

In contrast, according to exemplary embodiments of the present disclosure, under the assumption that a washing machine has a no-load imbalance value of 50 g (not arbitrarily chosen, but actually measured and stored as an offset value in the memory), and a maximum load imbalance value of 600 g, the control unit 214 may set the threshold load imbalance value of the washing machine to 550 g by subtracting the no-load imbalance value of 50 g from the maximum load imbalance value of 600 g, thereby maximizing the performance of the washing machine.

FIG. 3 is a flow chart of an exemplary process for setting the threshold load imbalance value of a washing machine in accordance with embodiment(s) of the present disclosure. Hereinafter, one or more exemplary embodiments of the present disclosure will be described in detail with reference to FIGS. 2 and 3.

After the drum 202 and the drum driving motor 204 are assembled during the manufacturing process of the washing machine 200 in step S300, the drum driving motor 204 is driven in step S302. In this step S302, the drum 202 is in a no-load state, containing no laundry therein (e.g., the drum 202 is empty). Thereafter, under the no-load state, the no-load imbalance value 210 of the drum 202 is measured, calculated or otherwise determined in step S304.

An imbalance may occur even under the no-load state, and the imbalance may differ among different washing machines, depending on the tolerance of a counter electromotive force of the drum driving motor 204 and/or the conditions during assembly of the driving unit (including the drum, a shaft connected or coupled to the drum, a bearing for the shaft, etc.) in the washing machine.

In accordance with embodiment(s) of the present disclosure, in step S306, the determined and/or calculated no-load imbalance value 210 is stored in the memory 208. The no-load imbalance value 210 is generally used as an offset value for adjusting the threshold load imbalance value 212 of the washing machine.

Next, the threshold load imbalance value 212 is calculated as described herein using the stored offset value (i.e., the determined and/or calculated no-load imbalance value 210 of the washing machine) in step S308, and the calculated threshold load imbalance value 212 is stored in the memory 208 in step S310. The threshold load imbalance value 212 may be a different and/or a unique value for each individual washing machine, but some washing machines of the same type or model may have the same threshold load imbalance value 212 (e.g., when the have the same no-load imbalance value 210 and the same maximum load imbalance value).

In this regard, the threshold load imbalance value 212 of the washing machine 200 may be calculated by subtracting the no-load imbalance value 210 from the maximum load imbalance value. The calculated threshold load imbalance value becomes a reference value to determine whether to continue or stop the rotation of the drum 202 when an imbalance occurs when laundry is in the drum 202 (a “load state”).

Also, when an imbalance in the load state occurs, the threshold load imbalance value 212 stored in the memory 208 will be used as a reference value for the imbalance control operation performed by the control 214.

To put it another way, for example, when an imbalance occurs during the operation of the washing machine 200, after calculating, measuring or otherwise determining the actual load imbalance value caused by such imbalance, the control unit 214 compares the determined and/or calculated actual load imbalance value with the threshold load imbalance value 212, which reflects the characteristics of the washing machine 200, to determine whether to continue or stop the rotation of the drum 202, thereby maximizing the performance of the washing machine 200 in comparison with the prior art.

As described earlier, the threshold load imbalance value of one type or model of washing machine in accordance with the prior art is a single value, and the single value is smaller than its maximum load imbalance value by a fixed marginal value for that washing machine type or model (e.g., the maximum value of the no-load imbalance values for that type or model of washing machine), thereby failing to maximize the performance of all of the washing machines.

However, in accordance with exemplary embodiments of the present disclosure, the washing machine 200 according to exemplary embodiments of the present disclosure sets its threshold load imbalance value to the one calculated by subtracting the no-load imbalance value 210 of the individual washing machine 200, which is measured under the no-load state, from the maximum load imbalance value, thereby being able to set the threshold load imbalance value 212 in consideration of the innate or intrinsic characteristic of the individual washing machine.

For example, in a group of washing machines of the same type and/or model having a no-load imbalance value in the range of 50 g to 150 g, and a maximum load imbalance value of 600 g, the control unit 214 of a washing machine having a no-load imbalance value of 50 g according to exemplary embodiments of the present disclosure sets the threshold load imbalance value intrinsic to such washing machine to 550 g. The value is obtained by subtracting the no-load imbalance value of 50 g from the maximum load imbalance value of 600 g, thereby maximizing the performance of a washing machine.

As described above, in accordance with exemplary embodiments of the present disclosure, it is possible to maximize the performance of a washing machine by controlling an imbalance of the washing machine by measuring or otherwise determining the no-load imbalance value for the washing machine (e.g., in view of the tolerance of the counter electromotive force of the drum driving motor in the washing machine, and/or the conditions under which the driving unit including a drum, shaft, bearing, etc., are assembled), and the measured no-load imbalance value may be an offset value to adjust the threshold load imbalance value in order to maximize the performance of the washing machine.

Although exemplary embodiments of the present disclosure are described above with reference to the accompanying drawings, those skilled in the art will understand that the present disclosure may be implemented in various ways without changing the necessary features or the spirit of the present disclosure.

Therefore, it should be understood that the exemplary embodiments described above are not limiting, but only an example in all respects. The scope of the present disclosure is expressed by claims below, not the detailed description, and it should be construed that all changes and modifications achieved from the meanings and scope of claims and equivalent concepts are included in the scope of the present disclosure.

From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. The exemplary embodiments disclosed in the specification of the present disclosure do not limit the present disclosure. The scope of the present disclosure will be interpreted by the claims below, and all techniques within the scope equivalent thereto belong to the scope of the present disclosure. 

What is claimed is:
 1. A drum type washing machine comprising: a drum; a motor configured to rotate the drum; a memory configured to store a no-load imbalance value of the washing machine and a threshold load imbalance value of the washing machine, wherein the no-load imbalance value is measured from an imbalance occurring during a rotation of the drum having no laundry in it; and a control unit configured to calculate the threshold load imbalance value using the measured no-load imbalance value, and compare an actual load imbalance value with the threshold load imbalance value and determine whether to stop a rotation of the drum based on the comparison, wherein the actual load imbalance value is determined from an imbalance occurring during rotation of the drum having laundry therein.
 2. The washing machine of claim 1, wherein control unit calculates the threshold load imbalance value by subtracting the no-load imbalance value from a maximum load imbalance value of the washing machine.
 3. The washing machine of claim 2, wherein the maximum load imbalance value is a pre-determined value in accordance with a specification for the washing machine.
 4. The washing machine of claim 3, wherein the maximum load imbalance value is a limit beyond which the washing machine cannot withstand any more the imbalance occurring during rotation of the drum having laundry therein.
 5. The washing machine of claim 3, wherein other washing machines are manufactured according to the specification.
 6. The washing machine of claim 5, wherein the no-load imbalance value is equal to or different from that of another washing machine manufactured according the specification.
 7. The washing machine of claim 6, wherein the no-load imbalance value depends on characteristics of a motor in the washing machine and tolerance variations in manufacturing and assembling of the washing machine.
 8. A method for calculating a threshold imbalance value of a drum type washing machine comprising: measuring a no-load imbalance value from an imbalance occurring during a rotation of a drum having no laundry therein; setting the no-load imbalance value as an offset value to adjust a threshold load imbalance value of the washing machine; calculating the threshold load imbalance value of the washing machine using the no-load imbalance value; and storing the calculated threshold load imbalance value.
 9. The method of claim 8, wherein calculating the threshold load imbalance value comprises: reading a maximum load imbalance value of the washing machine; and subtracting the no-load imbalance value from the maximum load imbalance value.
 10. The method of claim 9, wherein the maximum load imbalance value of the washing machine is a pre-determined value in accordance with a specification for the washing machine.
 11. The method of claim 10, wherein the maximum load imbalance value is a limit beyond which the washing machine cannot withstand any more the imbalance occurring during rotation of the drum having laundry therein.
 12. The method of claim 10, wherein other washing machines are manufactured according to the specification.
 13. The method of claim 8, wherein the no-load imbalance value of the washing machine equals or is different from that of another washing machine manufactured in accordance with the specification.
 14. The method of claim 13, wherein the no-load imbalance value depends on characteristics of a motor of the washing machine and tolerance variations in manufacturing and assembling the washing machine. 